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CC > CC LAB EXPE 8 > Flashcards

CC LAB EXPE 8 Flashcards

1
Q

Amylase was first measured quantitatively by an _____ introduced by ______

A

Iodometric method; by Wohlegemuth

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2
Q

Who introduced a procedure in 1938 that standardized the amounts of starch and iodine?

A

Somogyi

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3
Q

His work became the basis for the widely used amyloclastic and saccharogenic methods introduced in 1956 and 1960

A

Somogyi

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4
Q

What are the disadvantages of the methods used by wohlegemuth and Somogyi?

A

Long incubation times, endogenous glucose interference, and unstable reaction colors resulting in poor reproducibility and reliability

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5
Q

Wallenfels et Al introduced____ as defined substrates for amylase determination in a procedure that eliminated interference from endogenous glucose and pyruvate

A

P-nitrophenylglycosides

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6
Q

The present procedure is based on modifications of Wallenfels, using a substrate ________ with the terminal glucose blocked to reduce spontaneous degradation of the substrate by ____ and _____

A

P-nitrophenyl- D-maltoheptaoside (PNPG7); glucosidase and glucoamylase

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7
Q

The determination of amylase activity in serum and and urine is most commonly performed for the diagnosis of _____

A

Acute pancreatitis

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8
Q

True or False: in acute pancreatitis, amylase levels are elevated for longer periods of time in serum than in urine

A

False: in acute pancreatitis, amylase levels are elevated for longer periods of time in urine than in serum

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9
Q

_____ hydrolyzes PNPG7 to PNPG3 and _____

A

Amylase; Maltotetraose

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10
Q

____ hydroxides PNPG3 to PNPG1 and glucose

A

Glucoamylase

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11
Q

___ hydrolyzed to glucosidase to glucose and p-nitrophenol, which produces a _____ color

A

PNPG1; Yellow color

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12
Q

The rate of increase in absorbance of p-nitrophenol is measured at _____ and is ____ to the amylase activity in the sample

A

405nm; directly proportional

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13
Q

PNPG3 +____

A

Matlotetraose

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14
Q

PNPG1 +____

A

Glucose

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15
Q

P-nitrophenol + ____

A

Glucose

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16
Q

Assay for amylase involves the determination of both ______ and the _____

A

Salivary amylase and pancreatic amylase

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17
Q

This method measure the breakdown of starch substrate

A

Amyloclastic method

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18
Q

What are under amyloclastic methods

A

Viscosimetric
Iodometric
Turbidimetric
Nephelometric

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19
Q

An instrument used to measure the change in flow rate of starch

A

Viscosimeter

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20
Q

This procedure involves the hydrolysis of starch that results in the disruption of its molecular structure with reduction of viscosity

A

Viscosimetric

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21
Q

This method are very inaccurate, highly dependent on the nature of starch substrate and unsuitable for the measurement of low amylase activities

A

Viscosimetric

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22
Q

This procedure measure the decrease in absorbance of a turbid starch substrate due to reduction in starch granule size as a result of amylase activity.

A

Turbidimetric

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23
Q

These methods are simple and rapid, but poor in precision at near normal activity of amylase and inadequate substrate stability.

A

Turbidimetric

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24
Q

True or False: the Turbidimetric change is linearly related to amylase activity, except perhaps in the first two minutes of the reaction

A

The Turbidimetric change is NOT linearly related to amylase activity, except perhaps in the first two minutes of the reaction

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25
Q

What procedure involves; The endpoint is indicated by the absence of the blue-starch iodine color

A

Iodometric

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26
Q

Only___ gives a blue color with iodine, ____ forms a weak red color

A

Amylose; Amylopectin

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27
Q

The characteristic blue color is due to the helical configuration which amylose forms with iodine; each turn of helix contains ___ glucose units and surrounds __ molecule of iodine

A

6 glucose units and 1molecule of iodine

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28
Q

The blue color is obtained only when the overall chain length of amylose is greater than ____

A

45 glucose units

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29
Q

What are the disadvantages of Iodometric Methods

A

-only the hydrolysis of the amylose portion of the starch is being measured yet amylase has greater activity in hydrolyzing amylopectin
- starches of different origin vary in their proportions of amylose and amylopectin
- amylase does not act under the substrate saturation conditions
- interference from proteins, particularly albumin, and from lipids

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30
Q

___ based on reduction of light-scattering of starch substrate by amylase activity

A

Nephelometric assays

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31
Q

What are the advantages of Nephelometric Approach

A

Simplicity, Speed, Precision, and Zero Order kinetics

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32
Q

It is claimed to be suitable for emergency purposes, results being available in less than 3 minutes with direct read-out, bench working time and manipulation are minimal, sample blanking is NOT required

A

Nephelometric

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33
Q

In this method, a starch bound to a dye is hydrolyzed by amylase with the release of dye-substrate fragments which are water soluble

A

Chromogenic Methods

34
Q

This method is based on the hydrolysis of starch by amylase to produce carbohydrates that have reducing properties

A

Saccharogenic Method

35
Q

To convert Somogyi units to IU, multiply values by _____

A

1.85

36
Q

This involves the measurement of amylase activity by HLPC with fluorescence detection, using a fluorogenic substrate

A

Fluorogenic methods

37
Q

HPLC product analysis revealed a treated production of substituted oligosaccharide by ____ than by ____, and this observation was used as a the basis of a differential assay for these isoamylases in ____

A

Pancreatic; salivary amylase ; Human serum

38
Q

This method involves the usage of fluorescein-labeled amylose

A

Fluorescence Depolarization Method

39
Q

Fluorescence Depolarization Method: the degree of polarization of light emitted from this fluorophore when excited by a polarized beam of light is ____ by amylase ____

A

Decreased; hydrolysis

40
Q

True or False: (Fluorescence Depolarization Method) : The smaller molecules formed are less polarized because they rotate faster than the intact substrate

A

True

41
Q

This method is the basis of the Abbott TDX Amylase assay and this method provides a simple and sensitive direct assay but requires special instrumentation

A

Fluorescence Depolarization Method

42
Q

This method is for measuring amylase activity using radio labeled starch substrate

A

Radiometric Method

43
Q

Amylase Hydrolysis of the radio-labeled substrate releases ____ which is ___ proportional to amylase activity

A

Free radioisotope; proportional

44
Q

This method involves immunoassay using polyclonal antibodies produced against salivary or pancreatic isoamylase as antigen

A

Immunologic Method

45
Q

Maltopentose ——> maltotriose + maltose

A

Amylase

46
Q

Maltotriose + maltose ——> glucose

A

Alpha glucosidase

47
Q

Glucose + ATP ——-> glucose-6-phosphate + ADP

A

Hexokinase

48
Q

Glucose-6-phosphate + NAD ——-> 6-phosphogluconolactone + NADH

A

G6PD

49
Q

The IFCC has optimized this method at 37C, recommending it as a reference method for amylase determination

A

5 ethylidene- 4- nitrophenyl glycosides as subtrates

50
Q

This involves the use of 2-chloro-p-nitrophenol as an indicator

A

Use of 2-chloro-p-nitrophenyl- alpha-D-maltotrioside as substrate

51
Q

Disadvantages of 2-chloro-p-nitrophenyl-D-alpha-matlotrioside as a subtracted

A

Slow reaction rate
Variation in molar absorptivity of chloro-p-nitrophenol associated with changes in pH
Temperature
Protein content
Presence of potassium thiocyanate = allosteric changes to amylase and precluding the use of antibodies for p-amylase determination

52
Q

True or false: In amylase determination, heparinized plasma can also be used

A

True

53
Q

Anticoagulants such as ______, ______, and _____ should NOT be used as these bind to calcium (an ion needed for amylase activity) , this May lower amylase activity (EDTA by 10%)

A

Citrate
EDTA
Oxalate

54
Q

Urine specimens should be collected for a ____, adjusted to a pH of ___ with either 0.1N NaOH or 0.1 HCl and kept refrigerated until assayed

A

24 hour period, ph 7

55
Q

Amylase in serum and urine is reported stable for ____ at ____ and for several months when stored at _____ degrees Celsius and protected against evaporation and bacterial contamination.

A

1 week at RT; 2-8C

56
Q

Stability may decrease in urine samples with ph less than ____

A

5

57
Q

What causes the increase in pancreatic amylase in serum?

A

Macroamylasemia
Lipemia
Bilirubin concentration greater than 20 mg/dL (falsely increase)
Insulin and some bacteria
Administration of morphine and opiates (falsely increase)

58
Q

Contamination of sample with ___ and ____ should be avoided as these contain alpha-amylase

A

Sweat and saliva

59
Q

What is the linearity of the method?

A

1,500 IU/L

60
Q

What are the isoenzymes of amylase?

A

Pancreatic and Salivary fractions

61
Q

What methods can be used to differentiate the isoenzymes of amylase?

A

Electrophoresis
Ion exchange chromatography
Isoelectric focusing
Selective inhibition of S-AMY by a wheat germ inhibitor
Immuno precipitation by a monoclononal antibody
Immune inhibition

62
Q

Only methods based on selective isoenzyme inhibition by monoloclonal antibodies have shown sufficient——-

A

Precision
Reliability
Practicability
Analytical speed to allow the introduction of P-AMY determination into a clinical practice

63
Q

WHAT IS ACCR?

A

Amylase-creatinine clearance ratio

64
Q

It was established as an index for screening of acute pancreatitis

A

ACCR (Amylase-Creatinine Clearance Ratio)

65
Q

ACCR is increased in cases of _______________

A

Diabetes keto acidosis
Renal insufficiency
Severe burns

66
Q

Reference range of ACCR?

A

1-5%

67
Q

Reagent composition of AMYLASE DETERMINATION

A

P-nitrophenyl-D-Maltoheptaoside
Glucosidase-yeast
Glucoamylase- rhizopus spp.
Sodium chloride
Calcium chloride
Buffer
PH

68
Q

P-nitrophenyl- D- Maltoheptaoside (____)

A

0.9 mM

69
Q

Glucosidase- yeast (_____)

A

25, 000 IU/L

70
Q

Glucoamylase- rhizopus spp (___)

A

10,000 IU/L

71
Q

Sodium chloride [____]

A

50mM

72
Q

Calcium chloride (_____)

A

5 mM

73
Q

Buffer (___)

A

50 mM

74
Q

Ph [______]

A

6.9

75
Q

TV=

A

1.025

76
Q

MMA=

A

8.5

77
Q

SV=

A

0.025 mL

78
Q

Multiplication factor of AMYLASE

A

4824

79
Q

Linearity of amylase

A

1,500 IU/L

80
Q

Expected values in serum

A

Up to 96 IU/L

81
Q

Expected values in urine

A

18-330 IU/L

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